1. Field of the Invention
The present invention relates to air-conditioning ducts for vehicles.
2. Description of the Related Art
Conventional box-shaped minivan, station wagon and the like having large passenger compartment space are provided with an air-conditioning unit not only in the front part of a vehicle but also in the rear part of the vehicle in order to achieve uniform air-conditioning of the whole vehicle.
Such an air-conditioning unit provided in the rear part of the vehicle is generally embedded in the inside of one of the side walls of the rear passenger compartment.
Air-conditioning air passes under the floor or through the ceiling, and is uniformly supplied to backseats on both sides through air-conditioning ducts provided along roof sides or side trims on both sides.
In general, space to dispose air-conditioning ducts is restricted by design and limited in space due to relationship with other parts.
Moreover, air-conditioning ducts are connected by sequentially splicing subdivided unit ducts corresponding to each unit for reasons relating to molding or assembly of each unit of vehicles.
Furthermore, there are techniques to connect a plurality of ducts to an air-conditioning unit to provide a first ventilation flue and a second ventilation flue in order to supply air-conditioning air supplied from the air-conditioning unit to intended positions (See, for example, JP. A. 6-106956)
Moreover, unit ducts are connected by forming a flange at the end of each duct body, and connecting the formed flanges via a seal material as described in JP. A. 2004-249826.
Use of this method allows connecting ducts by fitting one duct over another duct, achieving easy connection of unit ducts even when the connection of ducts must be performed at a place that cannot be visually monitored when assembling vehicle units.
However, when incorporating the air-conditioning ducts in parallel to form a first ventilation flue and a second ventilation flue, better blowing efficiency of the first ventilation flue and the second ventilation flue through which air-conditioning air passes in a predetermined space to dispose air-conditioning ducts, and better airtightness at connection parts of the air-conditioning ducts is difficult to achieve at the same time.
In other words, in a case of supplying each side of the rear seat of a vehicle with air-conditioning air with different temperatures from the air-conditioning unit, the air-conditioning unit must be provided with a duct at each supply outlet of the air-conditioning unit with, for example, one duct extended to the right-side seat, while the other duct extended to the left-side seat.
In this case, between the position to branch the ducts towards the seats on both sides and the supply outlet of the air-conditioning unit, each duct will form a first ventilation flue and a second ventilation flue incorporated in parallel. Providing a joining section to connect ducts in the above-mentioned area poses the following problem.
When connecting incorporated unit ducts 100 and 101 to other incorporated unit ducts 100 and 101, the ducts are provided with flanges 102 at their ends, and contacted via a seal material 300. As shown in FIG. 4 and FIG. 5, if the seal material 300, such as a packing, is wound without providing a flange at a boundary wall T of both ducts incorporated for better blowing efficiency, enough sealing property cannot be obtained since the boundary wall T is but-jointed.
That is, air-conditioning air in one ventilation flue flows into the other ventilation flue through the gap generated at the joining section, causing, what is called, an air leakage phenomenon.
As a result, the air-conditioning air flowing through the first ventilation flue S1 and the air-conditioning air with a different temperature flowing through the second ventilation flue S2 are mixed to cause lower thermal efficiency.
The present invention was developed to solve the above-mentioned problem. That is, an object of the present invention is to provide an air-conditioning duct with excellent blowing efficiency which does not cause an air leakage phenomenon when air-conditioning ducts are connected and fixed.